The judges granted a request Thursday by the 18 voters to join the lawsuit as defendants, along with two senior state elections officials under Democratic Gov. Tom Wolf.

The decision came during a session to sort out issues ahead of a hearing next week.

The GOP congressmen argue the state Supreme Court exceeded its authority in declaring the 6-year-old map unconstitutional, and didn’t give state legislators enough time to develop a replacement before the court imposed its own map.

The 2011 Republican-drawn map was widely considered among the nation’s most gerrymandered, as GOP candidates dominated Pennsylvania’s congressional races in the three elections since.